Add emulation of C++14's std::make_unique

Unlike std::make_shared, std::make_unique was unfortunately missing from
C++11. It's a useful utility though.
Technically, declaring a new name in the std namespace is undefined, but
the other way to make make_unique available to all callers regardless of
C++ version, putting it into a distinct utility namespace and importing
the declaration from std if available, makes for more ugly code.

CMakeLists.txt

@@ -89,6 +89,8 @@ REQUIRE_CXX_SOURCE_COMPILES("#include <memory>\nint main() { std::unique_ptr<int
 CHECK_CXX_SOURCE_COMPILES("void f(struct D&&); int main() { return 0; }" HAVE_RVALUE_REF)
 CHECK_CXX_SOURCE_COMPILES("int main() { void *d = nullptr; }" HAVE_NULLPTR)
 CHECK_CXX_SOURCE_COMPILES("int main() { static_assert(true, \"\"); }" HAVE_STATIC_ASSERT)
+CHECK_CXX_SOURCE_COMPILES("#include <memory>\nint main() { auto a = std::make_unique<int>(0); }" HAVE_MAKE_UNIQUE)
+CHECK_CXX_SOURCE_COMPILES("template<class... T> class C; int main() { return 0; }" HAVE_VARIADIC_TEMPLATES)
 
 # g++'s libstdc++ doesn't properly support <regex> until 4.9.
 # They ship a header that declares functions, but they don't ship an
@@ -1031,6 +1033,7 @@ src/platform/StdSchedulerPoll.cpp
 src/platform/StdScheduler.h
 src/platform/C4TimeMilliseconds.cpp 
 src/platform/C4TimeMilliseconds.h	
+src/platform/make_unique.h
 src/zlib/gzio.c
 src/zlib/gzio.h
 src/zlib/zutil.h

config.h.cmake

@@ -25,6 +25,9 @@
 /* Define to 1 if you have the <locale.h> header file. */
 #cmakedefine HAVE_LOCALE_H 1
 
+/* Define to 1 if your stdlib has std::make_unique */
+#cmakedefine HAVE_MAKE_UNIQUE 1
+
 /* Define to 1 if you have the <memory.h> header file. */
 #cmakedefine HAVE_MEMORY_H 1
 
@@ -100,6 +103,9 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #cmakedefine HAVE_UNISTD_H 1
 
+/* Define to 1 if your compiler supports variadic templates */
+#cmakedefine HAVE_VARIADIC_TEMPLATES 1
+
 /* Define to 1 if you have the `vasprintf' function. */
 #cmakedefine HAVE_VASPRINTF 1
 

src/platform/PlatformAbstraction.h

@@ -98,7 +98,8 @@ typedef ptrdiff_t ssize_t;
 #endif
 #endif
 
-
+// std::make_unique
+#include "platform/make_unique.h"
 
 #if defined(__GNUC__)
 // Allow checks for correct printf-usage

src/platform/make_unique.h

@@ -0,0 +1,72 @@
+/*
+ * OpenClonk, http://www.openclonk.org
+ *
+ * Copyright (c) 2015, The OpenClonk Team and contributors
+ *
+ * Distributed under the terms of the ISC license; see accompanying file
+ * "COPYING" for details.
+ *
+ * "Clonk" is a registered trademark of Matthes Bender, used with permission.
+ * See accompanying file "TRADEMARK" for details.
+ *
+ * To redistribute this file separately, substitute the full license texts
+ * for the above references.
+ */
+
+#ifndef INC_make_unique
+#define INC_make_unique
+
+#include "config.h"
+
+// C++14 std::make_unique
+#include <memory>
+#include <utility>
+#ifndef HAVE_MAKE_UNIQUE
+namespace detail {
+template<class T>
+typename std::enable_if<std::is_array<T>::value && std::extent<T>::value == 0, std::unique_ptr<T>>::type
+make_unique(size_t n)
+{
+	return std::unique_ptr<T>(new typename std::remove_extent<T>::type[n]());
+}
+
+#ifdef HAVE_VARIADIC_TEMPLATES
+template<class T, class ...Args>
+typename std::enable_if<!std::is_array<T>::value, std::unique_ptr<T>>::type
+make_unique(Args &&...args)
+{
+	return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
+}
+#else
+// We have to emulate variadic templates with preprocessor trickery.
+// Create a number of overloaded functions that handle this just like the
+// one function above. Works for up to _VARIADIC_MAX constructor arguments
+// (if you need more than 5, define that macro before including this header).
+#include <boost/preprocessor/inc.hpp>
+#include <boost/preprocessor/repetition/enum.hpp>
+#include <boost/preprocessor/repetition/enum_binary_params.hpp>
+#include <boost/preprocessor/repetition/enum_trailing_params.hpp>
+#include <boost/preprocessor/repetition/repeat.hpp>
+// This is the same macro that the MSVC STL also uses when it has to emulate
+// variadic templates, so it should work fine for our purposes
+#ifndef _VARIADIC_MAX
+#define _VARIADIC_MAX 5
+#endif
+
+#define MAKE_UNIQUE_FORWARDER(z, n, unused) std::forward<Arg ## n>(arg ## n)
+#define MAKE_UNIQUE_MAKER(z, n, unused) \
+	template<class T BOOST_PP_ENUM_TRAILING_PARAMS(n, class Arg)> \
+	typename std::enable_if<!std::is_array<T>::value, std::unique_ptr<T>>::type make_unique(BOOST_PP_ENUM_BINARY_PARAMS(n, Arg, &&arg)) \
+	{ \
+		return std::unique_ptr<T>(new T(BOOST_PP_ENUM(n, MAKE_UNIQUE_FORWARDER, unused))); \
+	}
+
+BOOST_PP_REPEAT(BOOST_PP_INC(_VARIADIC_MAX), MAKE_UNIQUE_MAKER, unused)
+#undef MAKE_UNIQUE_MAKER
+#undef MAKE_UNIQUE_FORWARDER
+#endif
+}
+namespace std { using ::detail::make_unique; }
+#endif
+
+#endif